1. Field of the Invention
This invention relates generally to the voice signal processing system and method. More particularly, this invention relates to a new apparatus and method for inputting voice to a voice processing system, such as a computer, which provide adaptive voice cancellation environment whereby interference generated by voice input can be prevented.
2. Description of the Prior Art
A major concern for implementing the speech receivers and processing systems for providing input to the computers, is the noisy environment. Particularly, when many computer users speak to their own computer simultaneously in an enclosed office. Additionally, the concern of privacy may prevent the use of voice input to a computer. For example, sitting on an airplane, the concern for bothering passenger sitting on the nearby seats or more vulnerable for passing out confidential information would hinder the use of a voice input system for a personal or laptop computer.
In U.S. Pat. No. 5,396,561, entitled xe2x80x9cActive Acoustic Attenuation and Spectral Shaping Systemxe2x80x9d (issued on Mar. 7, 1995), Popovich et al. disclose an active acoustic system to provide attenuation and spectral shaping of an acoustic wave. Techniques for active attenuation that involves canceling acoustic wave to destructively interfere with and cancel an input acoustic wave are disclosed. In an active acoustic attenuation system, the input acoustic wave is sensed with an error transducer, e.g., a microphone. The transducers then supplies the sensed error signals to a control model to generate a correctional signal. The correctional signal is provided to a canceling transducer such as a loudspeaker to cancel the input acoustic wave. The improvement of this system includes a phase lock loop locked to the input acoustic wave and then generates a desired signal in given phase relation with the input acoustic wave.
This active acoustic attenuation and spectral shaping system is very useful for an acoustic system, which receives voice input and undesirable noises as background information. The adaptive filter can be applied to cancel the noises by producing destructive interference signals. The active acoustic attenuation system as disclosed would be useful for a public announcing (PA) system or an acoustic recording chamber to filtering and canceling the undesirable noises.
However, such as system would not be useful to provide a solution for the difficulties faced by those using speed as an input means to a computer. Because in this situation, a speaker""s acoustic waves are propagated simultaneously to the input device and to the surrounding environment. The canceling acoustic wave generated and outputted from a canceling transducer, e.g., a loudspeaker, even with a small time delay, would be lagging behind the original acoustic wave issued from the speaker. Specifically, if the time delay for producing the canceling attenuation signals are xcex94t millisecond, and the sonic speed is S, then the canceling signal waves travel behind the original speaker""s voice by distance of D=Sxcex94t The canceling signals cannot catch up with the original sound waves from the speaker because both are propagating in the air with the same sonic speed.
Therefore, an acoustic attenuation and cancellation system as discussed above is not too useful for providing a quite environment for operation of multiple voice-input computers. A need still exists to provide a solution to resolve the difficulty of a noisy environment due multiple computer users speaking simultaneously to their own computer for providing voice input.
It is therefore an object of the present invention to provide a novel system configuration for attenuating and canceling voice input to a speech processor propagated to the surrounding space. A non-interfering and private environment can then be provided when acoustic signals are employed as means for providing input data to a computer such that the aforementioned limitations and difficulties encountered in the prior art can be overcome.
Specifically, it is an object of the present invention to provide a novel active acoustic attenuation and cancellation system arranged in a novel acoustic configuration to overcome the difficulty of the prior art The acoustic attenuation signals are first generated then provided to a cancellation transducer at a distance away from the original acoustic source for outputting at a proper time for canceling the original acoustic input propagated to the surrounding environment to that distance.
Another object of the present invention is to provide novel active acoustic attenuation and cancellation system arranged in a novel acoustic configuration by taking advantage of higher speed of signal transmission speed than sonic speed in the air. The cancellation signals are provided to a transducer at distance away from the original acoustic source. The cancellation signals are transmitted to the transducers earlier than the sound wave propagated to that distance. By controlling the time of outputting the cancellation signals at the time when the acoustic waves are propagated to that distance, effective acoustic cancellation can be carried out without affect the clear and precise input to the computers.
Another object of the present invention is to provide novel active acoustic attenuation and cancellation system arranged in a novel acoustic configuration by taking advantage of higher speed of wireless signal transmission than the sonic speed in the air. The cancellation signals are provided to a transducer at distance away from the original acoustic source by wireless signal transmission. The time of outputting the cancellation signals is controlled precisely at the time when the acoustic waves are propagated to that distance. Effective acoustic cancellation can be carried out without affect the clear and precise input to the computers.
Briefly, in a preferred embodiment, the present invention discloses an acoustic system that includes an input transducer for receiving an acoustic input signal from a speaker to a signal processing means. The acoustic system further includes means for providing a non-interfering environment. The means for providing non-interfering environment generates an acoustic cancellation signal for destructively interfering with the acoustic input signal at a distance away from the speaker. In a preferred embodiment, the means for providing a non-interfering environment further includes an acoustic attenuation means for generating a cancellation acoustic signal for destructively interfering with the acoustic input signal. In another preferred embodiment, the means for providing a non-interfering environment further includes a signal transmission means for transmitting the cancellation acoustic signal to the distance away from the speaker. In another preferred embodiment the signal transmission means is provided for transmitting the cancellation acoustic signal with a speed higher than an air sonic speed. In another preferred embodiment, the acoustic system further includes an output transducer for outputting the cancellation acoustic signal.